Electrolytic cell.



(No ModeL:

Patented Oct. 28, m2. ,A. E. TRUESDELL ELECTROLYTIC CELL.

(Application mm A i, 13, 1901.)

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UNIT D STATES PATENT OFFICE.

ARTHUREnTRUESDELL, OF PITTSFIELD, MASSACHUSETTS.

ELECTROLYTIC CELL.

SPECIFICATION forming part of Iletters Patent No. 712,218, dated October 2 8, 1902.

Application filed April is, 1901.

To all whom it may concern:

Be it known that I, ARTHUR E. TRUESDELL, a citizen of the United States of America, residing at Pittsfield, in the county of Berkshire and State of Massachusetts, have invented new and useful Improvements in Electrolytic Cells, of which the following is a specification.

This invention relates to electrolytic processes, the object thereof being the improvement of an electrolytic cell particularly adapted to the treatment of solutions containing salts of the alkaline metals. It is Well known that one of the principal difficulties in electrolyzing these solutions is due to the chemical affinity between the element sepa rated at the cathode on the one hand and the solvent of the salt and substances which the solvent may contain on the other hand. This action of the element on the solvent and others due to the presence in the solvent of the elements separatedat the anode are known as secondary reactions and are accompanied by the evolution of heat. Thesechem ical actions in the cell after the separation of the ions has begun are a distinct loss, as they consume energy and greatly lower the efficiency of the apparatus consideredas one adapted to the separation and recovery of the elements as such.

Of the many methods suggested and in use designed to overcome or prevent secondary reactions in electrolytic cells the method in which a cathode of mercuryis employed has met with much favor, since the metallic element of the salt immediately on separation from the solution combines with the mercury to form an amalgam, which amalgam is liquid when containing a small per cent. of the element, and therefore lends itself 'readily to mechanical displacement- If means are not employed for immediatelyremoving this element from a contact with the solution, chemical action Will take place between them, forming a new salt of the'element, which, if it be soluble, will enter again into the solution and again becomesubject to the electrolyzing action of the cell the same as in the first instance.

111 the referredto cells of the mercurial type, which are now largely in use, the chief drawbacksare, first, that the ion on separation does not readily combine with the merhcight of the ribs b above the floor.

Serial no. 55,700. (N0 model.)

cury, owing to the fact that the latter is in motion, or, second, that the removal of the amalgam as formed from contact with the so- .lution is neither positive nor complete.

The object of this invention is to prevent secondary reaction in the solution by first effecting the positive separation of the amalgam from the cathode-body; second, by reducing to the smallest possible area the point of contact of said amalgam with the solution; third, byapplying to said separated amalgam a current of electricity auxiliary to the main current of the cell, and, fourth, by the introduction of a recharged solution at or near the point of contact of'the separated amalgam with the solution.

In the drawings I showone form of construction embodying my invention whereby the improvements above recited may be practically carried out.

'Figure 1 is a vertical longitudinal section through an electrolytic cell embodying my invention. Fig. 2 is a sectional plan view on line 2' 2, Fig. 1. Fig. 3 is a sectional elevation on line 3 3, Fig. 1. Fig. 4isalongitudinal sectionon lined 4, Fig. 2. Fig. 5 is a perspective view of a portion of one of the sweepsdesigned to gather the amalgam.

Referring to the drawings, (it represents a vat or cell of any suitable material, such as slate or earthenware, having therein two oppositely-located ribs 19, of suitable material,

parallel with and near to the opposite sides of said vat or cell a and extending fromone end thereof to the other, leaving a channel 0 between the sidewall of the cell and said ribs. Covering the bottom of the cell between the ribsis located a floor d, of cast-iron, carbon, or other suitable conductor, said floor and said ribs, together with the end walls of the cells, constituting a rectangular depression adapted to contain a body of mercury (indicated by 6) whose depth is determined by the A reservoirfof mercury may be located at a convenient distance from the cell and connected through the floor-d by pipes g with the interior of the cell, the connection between the reservoir f and the pipes 9 being extensible, thereby permitting the raising and lowering of the reservoir for the maintenance of the level of the mercury within the cell. This vertical adjustment may be effected by screwing the reservoir in and out of the end of the pipe g, and, if desired, this adjustment may be made automatic by a suitable connection with any part of the machine, whereby a periodic raising of the reservoir will cause an overflow of the mercurial cathode-body, and thereby effect the depositing of the amalgam formed on the surface of said body in the channels 0, from whence the amalgam is carried away through the pipes 71. When the removal of the amalgam is thus efiected by the raising of the level of the cathode-body, the sweep Z may be dispensed with. The preferable construction, however, is that shown in the drawings, which comprises means for mechanically sweeping the amalgam from the surface of the cathode-body into the channels 0, all as hereinafter described.

The bottom of the channel 0, between the ribs 1) and the sides of the cell a, is, as shown in Fig. 4 and by dotted lines in Fig. 1, made to converge, preferably, at two points in the channel, and at the lowest point of said convergence is located a pipe h, which is trapped, as shown in Fig. 3, and which leads to any suitable point where the separation of the amalgam into its constitutent elements takes place, the mercury which is set free being returned eventually to the reservoirf and the element separated from the solution treated as may be desired.

It is very important that after the amalgam has been separated from the cathode-body its point of contact with the solution should be reduced to the smallest possible area and that said point of contact should be well removed from the anode, and to that end the pipes h are located as described, and the area of the exposure of the amalgam equals only the area of the pipe h in cross-section.

Pipes 1) serve for the introduction into the cell of the charged solution which fills the cell up to the overflow-pipe v, another pipe to being introduced into the cell to provide for the escape of any gas which may be formed.

70 represents carbon anodes, preferably arranged, as shown in Fig. 3, in'double rows'extending down through the cover of the cell and being supported thereby, the'T-heads of said anodes being submerged in the solution and extending transversely of the cell. The particular shape and manner of support of the anodes is immaterial, however. A barj, preferably of copper, embraces the ends of the anodes, which project through the cover of the cell, and is in electrical communication with the source of electricity which operates the cell.

The before-referred-to means for mechanically removing the amalgam which forms on the surface of the cathode-body consists of a sweep or scraper bar Z, shown in its relation to the cell in Figs. 2 and 3, and an enlarged perspective View of a portion thereof is shown in Fig. 5. Thisv bar is preferably made of glass, porcelain, or other suitable substance, supported on the floor d of the container by the feet 10, formed on the lower edge of the bars, which rest on said floor. This sweep extends lengthwise of the container and in any suitable manner may be given a movement transversely of the cell toward the channel cby any suitable means. The means shown in the drawings consist of wires m, extending through suitable stuffing-boxes n in the sides of the cell and connected with the sweep. These wires may be wound around or pass over pulleys 0, located on opposite sides of the cell, supported on suitable shafts, to which motion may be imparted in any desirable way to effect said traverse motion of the sweep either at a continuous speed or periodically, as desired.

The main source of electricity is indicated by g, from the positive role of which a wire connection 0 extends to the bars j and from the negative pole of which a wire connection 5 is carried to the floor of the container.

Of course when the vat is in operative position it is filled with the solution up to the height of the overflow-pipe n, which solution covers the entire cathode-bod y. The pipes it, through which amalgam is discharged, have their traps sealed by said amalgam. Fresh amalgam as it is swept from time to time into the channel 0 will run into the discharge-pipe and displacing a part of the amalgam forming the seal of the trap takes its place in the latter, thus preventing the passage of solution therethrough, but taking care of the amalgam as it is received.

It will be observed that as the amalgam is removed from the cathode-body it does not come to a state of rest until it reaches the trap in the pipes h, and herein lies one of the novel features of the invention, for by the removal of the amalgam in the manner described its contact with the solution is reduced to the cross-sectional area of the pipe h, and that contact is at a point well removed from the anode, and therefore the opportunity for reaction is much limited. To prevent as far as possible the effect of even this limited contact with the solution, an auxiliary source of electricityt is provided whose positive pole is connected into the line r, running to the anodes, but whose negative pole is connected, as at u, with the amalgam which always fills the trap in the discharge-pipe 72, and the current from this auxiliary source by well-known means may be so regulated as to density as to practically reduce to a minimum any reaction due to the contact of the solution with the amalgam in the discharge-pipes. Furthermore, it has been found in practice that by efiecting the inflow of fresh solution through the pipes i at the bottom or substantially the bottom of the incline within the channel 0 and permitting it to flow upward therefrom into the cell tends to largely counteract the IIO tendency to reaction of the amalgam within. the discharge-pipe or of the amalgam accumulating on the top of the pond of mercury.

The reason for introducing the fresh solution in the immediate neighborhood of the removed amalgam is because the fresh solution contains fewer elements calculated to react on the amalgam than does the solution in the cell which has been subjected to the decomposing action of the electric current. The introduction of this'solution at the point described and the restriction of the area of the separated amalgam to as great a degree as is practicable greatly reduce the probability of 1 5 reaction of the amalgam or, more properly, of

the elements therein contained.

From the above description it is seen that means are employed for removing positively the amalgam from the surface of the mercury as rapidly as desired into the channel, from whence it is run into discharge-pipes, whereby it is removed almost entirely from contact with the solution, and during this movement continually subjected to influences for preventing its decomposition and reaction on the solution, first, bythe contact of the inflowing recharged solution and, second, by the connections u with the auxiliary source t of electricity, and the result is a continuously-acting cell free from the objections referred to above as inherent in the type of cells now in use.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

l. The combination in an'electrolytic apparatus, of a vat, a fluid-metal cathode, a container therefor, a suitable anode, a source of electricity, suitable connections from said source to said cathode and anode, whereby, under operative conditions, an amalgam-may be formed on'said cathode, a channel having an inclined bottom at the side of. said container, means forremoving said amalgam to said channel, an outlet from thelowest point in the latter and a trap in said outlet, substantially as described.

2. The combination in an electrolytic ap paratus, of a vat, a body of mercury therein constituting a cathode, a container for said mercury, a channel having an inclined bottom at the side ofsaid container, a sweep for brushing the surface of said mercury in the direction of said channel, an outlet at the lowest point in the latter, a trap in said outlet, and a pipe in said vat located in proximity to said outlet for the introduction'of solution; suitable anodes in the vat, and electrical connections between said anodesand cathode, substantially as described.

3. The combination in an electrolytic apparatus, of a vat, a cathode of mercury, a container for said cathode, a suitable channel in the side of the container, and a dischargepipe in said channel, and a trap in the discharge-pipe; an anode, a main source of elec-- tricity and an auxiliary source of electricity,

suitable connections between said main source to the anode and the cathode, and connections from said. auxiliary source toithe anode and to said trap in the outlet-pipe, and

means operating on the surface of the cathode whereby an amalgam formed thereon may be separated therefrom and carried into said channel, said outlet-pipe, and said trap, all substantially asdescribed. V

4. The combination in an electrolytic apparatus, of a vat, a cathode Ofmercury, a suitable anode, a source of electricity, electrical connections between said anode and cathode whereby, under operative conditions, an amalgam will be formed on said cathode, means for separating said amalgam from the cathode, an outlet'from the vat for said amalgam, a trap in said outlet for retaining apart of the amalgam, a second source of electricity connected through'its positive pole to said anode and through its negative pole with the interior of the trap, substantially as described.

5. The combination in an electrolytic apparatus of the class described, comprising a vat adapted to contain a solution to be acted upon, a suitable anode, a cathode of mercury, andsuitable electrical connections withsaid anode and cathode whereby, under operative conditions, a' mercurial amalgam may be formed on said cathode; of means for effooting the separation of said amalgam from said cathode, an auxiliary electrical circuit, and connections therefrom to said anode and to said separated amalgam, substantially as described.

6. Inan electrolytic cell having fluidmetal cathode and suitable anodes whereby under operative conditions an amalgam may be formed on said cathode, a mainielectrical circuit connected with said anode and cathode, means for separatingth'e amalgam :fromseparating the amalgam from the cathode, an

auxiliary circuit through the separated amalgam, said amalgam constituting theca thode of said auxiliary circuit.

8. Inan electrolytic cell, wherein anamalgam is formed in the presence of the solution,

an anode and a cathode in the cell, a main circuit therefor, a channel, means for separating the amalgam from the cathode whereby it is deposited in said channel, a dischargepipe leading from said channel, and means for restrictingthe area of said separated amalgamto substantially the area of the dischargepipe, during the operation ofthe cell, and a column of the electrolyte maintained therein.

9. In an electrolytic cell wherein an amalgam is formed in the presence of the solution,

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an anode and a cathode in the cell, a main circuit therefor, a channel, means for sepa rating the amalgam from the cathode, wherebyit is deposited in said channel, a dischargepipe leading from the channel, and means whereby the area of separated amalgam exposed to the solution may be restricted substantially to the area of said discharge-pipe, and means for introducing fresh solution in the vicinity of that part of the separated amalgam so exposed.

10. In an electrolytic cell having a suitable cathode and a suitable anode whereby under operative conditions an amalgam may be formed on the cathode, a channel on the cell having an inclined bottom, means for separating the amalgam from the cathode and depositing it in said channel, and a trap located under the cell and entering said channel at its lowest point, substantially as described.

ARTHUR E. TRUESDELL. Witnesses:

J. TROY, O. G. TRUESDELL. 

